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Abstract:

Provided is a charged particle beam writing apparatus including a stage
which a sample can be mounted thereon, an irradiation unit which emits a
charged particle beam to be irradiated on the sample, and an aperture
plate which includes a first opening portion to shape the charged
particle beam. The aperture plate has a stacked structure of a first
member and a second member, and a position of an end portion of the first
opening portion in the second member is recessed from the position of the
end portion of the first opening portion in the first member.

Claims:

1. A charged particle beam writing apparatus comprising: a stage which a
sample can be mounted thereon; an irradiation unit which emits a charged
particle beam to be irradiated on the sample; and an aperture plate which
includes a first opening portion to shape the charged particle beam,
wherein the aperture plate has a stacked structure of a first member and
a second member, and a position of an end portion of the first opening
portion in the second member is recessed from the position of the end
portion of the first opening portion in the first member.

2. The charged particle beam writing apparatus according to claim 1,
wherein a charged particle beam transmittance of the second member is
smaller than that of the first member.

3. The charged particle beam writing apparatus according to claim 1,
wherein the aperture plate further includes a second opening portion
having an area smaller than that of the first opening portion and a third
opening portion having the same shape as that of the second opening
portion, and positions of end portions of the second and third opening
portions in the second member are respectively recessed from the
positions of the end portions of the second and third opening portions in
the first member.

4. The charged particle beam writing apparatus according to claim 1,
wherein, in the end portion of the first opening portion, an air gap
exists in an interface between the first member and the second member.

5. The charged particle beam writing apparatus according to claim 1,
wherein the first and second members are formed of the same material.

6. The charged particle beam writing apparatus according to claim 5,
wherein the first and second members are formed of silicon.

7. The charged particle beam writing apparatus according to claim 1,
wherein the first and second members are formed of different materials.

8. The charged particle beam writing apparatus according to claim 7,
wherein the first member is formed of silicon, and the second member is
formed of a high melting point metal.

9. A charged particle beam writing apparatus comprising: a stage which a
sample can be mounted thereon; an irradiation unit which emits a charged
particle beam to be irradiated on the sample; and an aperture plate which
includes a plurality of opening portions to form multi-beams by allowing
a region including all the plurality of opening portions to be irradiated
with the charged particle beam and allowing portions of the charged
particle beam to pass through the plurality of opening portions, wherein
the aperture plate has a stacked structure of a first member and a second
member, and a position of an end portion of the opening portion in the
second member is recessed from the position of the end portion of the
opening portion in first member.

10. The charged particle beam writing apparatus according to claim 9,
wherein a charged particle beam transmittance of the second member is
smaller than that of the first member.

11. The charged particle beam writing apparatus according to claim 9,
wherein, in the end portion of the first opening portion, an air gap
exists in an interface between the first member and the second member.

12. The charged particle beam writing apparatus according to claim 9,
wherein the plurality of opening portions each have the same dimension
and shape.

13. The charged particle beam writing apparatus according to claim 9,
wherein the first and second members are formed of the same material.

14. The charged particle beam writing apparatus according to claim 13,
wherein the first and second members are formed of silicon.

15. The charged particle beam writing apparatus according to claim 9,
wherein the first and second members are formed of different materials.

16. The charged particle beam writing apparatus according to claim 15,
wherein the first member is formed of silicon, and the second member is
formed of a high melting point metal.

17. A charged particle beam writing method comprising: mounting a sample
on a stage; emitting a charged particle beam to the sample; and shaping
the charged particle beam by using an aperture plate including a first
opening portion, wherein the aperture plate has a stacked structure of a
first member and a second member, and a position of an end portion of the
first opening portion in the second member is recessed from the position
of the end portion of the first opening portion in the first member.

18. The charged particle beam writing method according to claim 17,
wherein a charged particle beam transmittance of the second member is
smaller than that of the first member.

19. The charged particle beam writing method according to claim 17,
wherein the aperture plate further includes a second opening portion
having an area smaller than that of the first opening portion and a third
opening portion having the same shape as that of the second opening
portion, and positions of end portions of the second and third opening
portions in the second member are respectively recessed from the
positions of the end portions of the second and third opening portions in
the first member.

20. The charged particle beam writing method according to claim 17,
wherein, in the end portion of the first opening portion, an air gap
exists in an interface between the first member and the second member.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is based upon and claims the benefit of priority
from Japanese Patent Applications No. 2011-267800, filed on Dec. 7, 2011,
the entire contents of which are incorporated herein by reference.

[0003] A lithography technique is a very important process among
semiconductor manufacturing processes by which scaling-down of a
semiconductor device is achieved, because the lithography technique is a
process that generates a pattern of the device. Recently, according to
high integrity of LSI, circuit line width required for a semiconductor
device has been reduced year after year. In order to form a desired
circuit pattern on the semiconductor device, a highly-accurate master
image pattern (sometimes, referred to as a reticle or a mask) is needed.
Herein, since an electron beam writing technique intrinsically has
excellent resolution, the technique is used to produce a highly-accurate
master image pattern.

[0004] In the above-described electron beam writing, uniformity of line
width in more accurate sample plane, for example, a mask plane is
required. Herein, in the electron beam writing, electrons are charged in
a deflector, and thus, the electron beam is drifted, so that there occurs
a phenomenon that position accuracy of the writing is degraded.

[0005] In order to improve the position accuracy of the writing, it is
preferable that the drift of the electron beam is suppressed.

[0006] JP-A H06-120126 discloses a technique of manufacturing an aperture
plate by using tungsten having high electron beam blocking ability so as
to improve processing accuracy of an opening portion of the aperture
plate.

SUMMARY OF THE INVENTION

[0007] A charged particle beam writing (or "drawing") apparatus according
to one aspect of the present disclosure includes: a stage which a sample
can be mounted thereon; an irradiation unit which emits a charged
particle beam to be irradiated on the sample; and an aperture plate which
includes a first opening portion to shape the charged particle beam,
wherein the aperture plate has a stacked (or "laminated") structure of a
first member and a second member, and a position of an end portion of the
first opening portion in the second member is recessed from the position
of the end portion of the first opening portion in the first member.

[0008] A charged particle beam writing apparatus according to one aspect
of the present disclosure includes: a stage which a sample can be mounted
thereon; an irradiation unit which emits a charged particle beam to be
irradiated on the sample; and an aperture plate which includes a
plurality of opening portions to form multi-beams by allowing a region
including all the plurality of opening portions to be irradiated with the
charged particle beam and allowing portions of the charged particle beam
to pass through the plurality of opening portions, wherein the aperture
plate has a stacked structure of a first member and a second member, and
a position of an end portion of the opening portion in the second member
is recessed from the position of the end portion of the opening portion
in first member.

[0009] A charged particle beam writing method according to one aspect of
the present disclosure includes: mounting a sample on a stage; emitting a
charged particle beam to the sample; and shaping the charged particle
beam by using an aperture plate including a first opening portion,
wherein the aperture plate has a stacked structure of a first member and
a second member, and a position of an end portion of the first opening
portion in the second member is recessed from the position of the end
portion of the first opening portion in the first member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIGS. 1A and 1B are schematic diagrams illustrating a structure of
an aperture plate according to a first embodiment;

[0011] FIG. 2 is a diagram illustrating a concept of a configuration of a
writing apparatus according to the first embodiment;

[0012]FIG. 3 is a diagram illustrating operations of variable shaping
type electron writing according to the first embodiment;

[0013]FIG. 4 is a diagram illustrating a relationship between electron
transmittance and a thickness of a silicon film;

[0014]FIG. 5 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to a second embodiment;

[0015]FIG. 6 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to a third embodiment;

[0016] FIGS. 7A to 7C are diagrams illustrating a method of manufacturing
the aperture plate according to the third embodiment;

[0017]FIG. 8 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to a fourth embodiment;

[0018] FIGS. 9A and 9B are schematic diagrams illustrating a structure of
an aperture plate according to a fifth embodiment;

[0019] FIG. 10 is a schematic top diagram illustrating a structure of an
aperture plate according to a sixth embodiment;

[0020] FIG. 11 is a diagram illustrating a concept of a configuration of a
writing apparatus according to a seventh embodiment;

[0021] FIGS. 12A and 12B are schematic diagrams illustrating a structure
of an aperture plate according to the first embodiment; and

[0022]FIG. 13 is a cross-sectional diagram illustrating an aperture plate
in the related art.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] As a cause of occurrence of drift of the electron beam, existence
of electrons that pass through an aperture plate shaping an electron beam
and are scattered may be considered. In order to suppress the scattering
of the electrons, one solution may be to make the aperture plate thick.
However, there is a problem in that manufacturing accuracy of an end
portion (edge portion) of an opening portion of the aperture plate gets
worse, and thus, shaping accuracy of the electron beam is degraded.

[0024] Hereinafter, the embodiments will be described with reference to
the drawings. Hereinafter, in the embodiments, a configuration where an
electron beam is used as an example of a charged particle beam will be
described. However, the charged particle beam is not limited to the
electron beam, but a beam using other charged particles such as an ion
beam may be used.

[0025] In the specification, writing data is basis data of a pattern which
is to be written on a sample. The writing data is data obtained by
converting a format of design data generated through CAD or the like by a
designer into such a format that the data can be operated and processed
in a writing apparatus. A writing pattern of a figure or the like is
defined by coordinates of, for example, vertexes of a figure.

[0026] In addition, in the specification, in some cases, the same or
similar components are denoted by the same reference numerals.

First Embodiment

[0027] A charged particle beam writing apparatus according to an
embodiment includes a stage which a sample can be mounted thereon, an
irradiation unit which emits a charged particle beam to be irradiated on
the sample, and an aperture plate which includes a first opening portion
to shape the charged particle beam, wherein the aperture plate has a
stacked structure of a first member and a second member. In addition, a
position of an end portion of the first opening portion of the second
member is configured to be recessed from the position of the end portion
of the first opening portion of the first member.

[0028] The charged particle beam writing apparatus according to the
embodiment has a stacked structure of the first member and the second
member. In addition, the end portion of the opening portion of the first
member is configured to thin, so that the processing (or manufacturing)
accuracy of the end portion of the opening portion can be secured. On the
other hand, the second member of which the position of the end portion of
the opening portion is recessed from the position of the end portion of
the opening portion in the first member is stacked, so that electron beam
blocking ability of the aperture plate can be improved. Therefore, it is
possible to suppress electron beam drift occurring due to scattering of
the electrons passing through the aperture plate.

[0029] FIG. 2 is a diagram illustrating a concept of a configuration of a
writing apparatus according to the embodiment.

[0030] As illustrated in FIG. 2, the writing apparatus 100 includes a
writing unit 150 and a control unit 160. The writing apparatus 100 is an
example of the charged particle beam writing apparatus. The writing
apparatus 100 writes a desired pattern on a sample 101.

[0031] The writing unit 150 includes an electron barrel 102 and a writing
chamber 103. An electron gun 201, an illumination lens 202, a blanking
(BLK) deflector 212, a blanking (BLK) aperture plate 214, a first
aperture plate 203, the projection lens 204, a deflector 205, a second
aperture plate 206, an objective lens 207, and a deflector 208 are
disposed within the electron barrel 102.

[0032] In addition, an XY stage 105 is movably disposed within the writing
chamber 103. In addition, the sample 101 is mounted on the XY stage 105.
As an example of the sample 101, there is a mask substrate for an
exposing process of transferring a pattern on a wafer. As an example of
the mask substrate, there is a blank mask where no image is written.

[0033] The control unit 160 includes a driving circuit 108, a magnetic
disc device 109, a deflection control circuit 110, digital-to-analog
converters (DACs) 112, 114, and 116, a control calculator 120, and a
memory 121.

[0034] The writing data stored in the magnetic disc device 109 are input
to the control calculator 120. Information input to the control
calculator 120 or information during or after an operation process is
stored in the memory 121 on each occasion.

[0035] The memory 121, the deflection control circuit 110, and the
magnetic disc device 109 are connected to the control calculator 120 via
a bus (not illustrated). The deflection control circuit 110 is connected
to DACs 112, 114, and 116. The DAC 112 is connected to the BLK deflector
212. The DAC 114 is connected to the deflector 205. The DAC 116 is
connected to the deflector 208.

[0036] FIG. 2 illustrates components necessary for describing the
embodiment. It is obvious that the writing apparatus 100 typically
includes other necessary components.

[0037]FIG. 3 is a diagram illustrating operations of variable shaping
type electron writing according to the embodiment. Hereinafter, the
writing method of the writing apparatus 100 will be described with
reference to FIGS. 2 and 3.

[0038] An electron beam 200 is emitted from the electron gun 201 as an
example of the irradiation unit. The electron beam 200 emitted from the
electron gun 201 is illuminated on the entire first aperture plate 203
having a rectangular, for example, oblong hole through the illumination
lens 202.

[0039] A rectangular, for example, oblong opening portion 411 for shaping
the electron beam 200 is formed in the first aperture plate 203. Herein,
the electron beam 200 is shaped to have an oblong shape.

[0040] Next, the electron beam 200 having a first aperture plate image,
which passes through the first aperture plate 203, is projected on the
second aperture plate 206 through the projection lens 204. An opening
portion 421 for shaping the electron beam 200 passing through the opening
portion 411 to be in a desired rectangular shape is formed in the second
aperture plate 206.

[0041] The position of the first aperture plate image on the second
aperture plate 206 is controlled to be deflected by the deflector 205
(FIG. 2). Next, the electron beam is allowed to pass through a
predetermined portion of the opening portion 421, so that the shape and
dimensions of the beam can be changed. As a result, the electron beam 200
is shaped.

[0042] Next, the electron beam 200 having a second aperture plate image
which passes through the second aperture plate 206 is focused by the
objective lens 207 (FIG. 2) and is deflected by the deflector 208. As a
result, the electron beam is irradiated on the desired position of the
sample 101 on the continuously-moving XY stage 105.

[0043] The movement of the XY stage 105 is driven by the driving circuit
108. The deflection voltage of the deflector 205 is controlled by the
deflection control circuit 110 and the DAC 114. The deflection voltage of
the deflector 208 is controlled by the deflection control circuit 110 and
the DAC 116.

[0044] In this manner, a rectangular shape which can pass through both of
the opening 411 and the variable shaping opening 421 is written in the
writing region of the sample 101. A type of forming an arbitrary shape by
allowing the shape to pass through both of the opening 411 and the
variable shaping opening 421 is called a variable shaping type.

[0045] At an irradiation time t when a desired irradiation amount of the
electron beam 200 on the sample 101 is incident on the sample 101,
blanking is performed as follows. In other words, in order not to
irradiate the sample 101 with more than a necessary amount of the
electron beam 200, the electron beam 200 is deflected by, for example, an
electrostatic type BLK deflector 212, and the electron beam 200 is cut by
a BLK aperture plate 214. Therefore, the electron beam 200 does not reach
a surface of the sample 101. The deflection voltage of the BLK deflector
212 is controlled by the deflection control circuit 110 and the DAC 112.

[0046] In case of beam ON (blanking OFF), the electron beam 200 emitted
from the electron gun 201 propagates along a trajectory indicated by a
solid line in FIG. 2. On the other hand, in case of beam OFF (blanking
ON), the electron beam 200 emitted from the electron gun 201 propagates
along a trajectory indicated by a dotted line in FIG. 1. In addition, an
inner portion of the electron barrel 102 and an inner portion of the
writing chamber 103 are allowed to be in vacuum by a vacuum pump (not
illustrated), so that the inner portions thereof are in a vacuum ambience
of which the pressure is lower than the atmospheric pressure.

[0047] FIGS. 1A and 1B are schematic diagrams illustrating a structure of
the aperture plate according to the embodiment. FIG. 1A is a top diagram,
and FIG. 1B is a cross-sectional diagram taken along line AA of FIG. 1A.

[0048] In the embodiment, the aperture plate 10 of FIGS. 1A and 1B is
applied to the first aperture plate 203 and/or the second aperture plate
206 of FIGS. 2 and 3.

[0049] The aperture plate 10 includes a first opening portion 12. The
electron beam is allowed to pass through the first opening portion 12 to
be shaped. In the cross-sectional diagram of FIG. 1B, the size of the
first opening portion 12 is in a range of, for example, about 20 μm to
about 50 μm.

[0050] The aperture plate 10 has a stacked structure of the first member
14a and the second member 16a. In the embodiment, the second member 16a
is disposed in the electron gun 201 side. In other words, the upper
surface of the second member 16a is configured to be irradiated with the
electron beam. Furthermore, the first member 14a may be configured to be
disposed in the electron gun 201 side.

[0051] The first member 14a and the second member 16a are formed by using
the same material, for example, silicon. As a material which can be used
for semiconductor processes of the related art during the manufacturing
and of which impurities can be suppressed to be at a low concentration,
the silicon can be preferably used. Furthermore, a semiconductor such as
silicon nitride, silicon carbide, or silicon germanide, a metal, or a
metal compound may be used.

[0052] In addition, as illustrated in FIG. 1B, the position of the end
portion (edge of opening portion) of the first opening portion of the
second member 16a is recessed from the position of the end portion (edge
of opening portion) of the first opening portion of the first member 14a.
In other words, the opening portion of the second member 16a is larger
than the opening portion of the first member 14a, and the first member
14a and the second member 16a are so stacked that the end portions of the
opening portions do not overlap each other.

[0053]FIG. 13 is a cross-sectional diagram illustrating an aperture plate
in the related art. As illustrated in FIG. 13, in the case where the
aperture plate is configured with a single layer and the aperture plate
of the end portion of the opening portion is thin, the electrons passing
through the aperture plate are scattered and charged in the deflector, so
that the drift of the electron beam occurs.

[0054]FIG. 4 is a diagram illustrating a relationship between electron
transmittance and a thickness of a silicon film. Incidence energy of an
electron is assumed to be 50 keV. As obvious from FIG. 4, in the case
where the thickness of the silicon film is 1 μm, the electron
transmittance is 100%; and in the case where the thickness of the silicon
film is 5 μm, the electron transmittance is close to 90%. However, in
the case where the thickness of the silicon film is 20 μm, the
electron transmittance is 1% or less. In this manner, in terms of
suppression of electron transmission amount, the thickness of the
aperture plate of the silicon is preferably 20 μm or more.

[0055] Furthermore, if the aperture plate is configured to be thick, the
aperture plate is hard to be processed, so that the processing accuracy
of the end portion of the opening portion of the aperture plate is
deteriorated. Therefore, the beam shaping accuracy is deteriorated, so
that the writing accuracy is deteriorated. For example, in order to
obtain the processing accuracy suitable for the mask processing for
microfine semiconductor products, the thickness of the aperture plate is
preferably 5 μm or more.

[0056] In the embodiment, the film thickness of the end portion of the
opening portion of the first member 14a is configured to be, for example,
5 μm or less by putting the processing accuracy as priority. In
addition, the second member 16b of which the film thickness t2 of
the end portion of the opening portion is larger than the film thickness
t1 of the end portion of the opening portion of the first member 14a
is stacked, so that the charged particle beam transmittance of the second
member is smaller than that of the first member. Accordingly, it is
possible to sufficiently block the electrons from passing. Therefore, it
is possible to suppress drift of the electron beam while maintaining the
processing accuracy of the edge of the opening portion of the aperture
plate.

[0057] For example, in the case where the first member 14a and the second
member 16a are silicon, a sum of the film thickness t1 and the film
thickness t2 is preferably 20 μm or more.

[0058] The recessed amount (d in FIG. 1B) of the end portion of the
opening portion of the second member 16a from the end portion of the
opening portion of the first member 14a is preferably as small as
possible in terms of suppression of electron transmission amount. The
recessed amount d is preferably 5 μm or less, more preferably, 3 μm
or less.

[0059] Furthermore, if the recessed amount d is too small, in the case
where the first member 14a and the second member 16a are manufactured
through adhesion, the adhesion with the recessed amount secured is
difficult to perform. Therefore, the recessed amount d is preferably 0.5
μm or more, more preferably, 1 μm or more.

[0060] According to the charged particle beam writing apparatus of the
embodiment, it is possible to implement the charged particle beam writing
apparatus capable of securing shaping accuracy of the charged particle
beam and suppressing drift of the charged particle beam. In addition,
according to the writing method using the charged particle beam writing
apparatus of the embodiment, it is possible to perform writing at high
accuracy by securing the shaping accuracy of the charged particle beam
and suppressing drift of the charged particle beam.

Second Embodiment

[0061] The embodiment is the same as the first embodiment except that the
first member and the second member are formed by using different
materials. Therefore, descriptions on overlapping portions with the first
embodiment are not presented.

[0062]FIG. 5 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to the embodiment. The first
member 14b and the second member 16b of the aperture plate 20 are formed
by using different materials. In addition, the electron passage rate of
the second member 16b is smaller than the electron transmittance of the
first member 14b.

[0063] The first member 14b is formed by using, for example, silicon. In
addition, the second member 16b is formed by using a material (material
having large atomic weight) which electrons are harder to transmit than
silicon. For example, a high melting point metal which has high electron
blocking ability and cannot easily become contamination sources in the
writing apparatus such as molybdenum, tungsten, and tantalum is
preferably used.

[0064] According to the embodiment, a material which electrons are harder
to transmit than the first member 14b is used for the second member 16b,
so that the second member 16b can be configured to be thin.

Third Embodiment

[0065] The embodiment is the same as the first embodiment except that the
first member and the second member are formed by using the same
manufacturing method. Therefore, descriptions on overlapping portions
with the first embodiment are not presented.

[0066]FIG. 6 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to the embodiment. The first
member 14c and the second member 16c of the aperture plate 30 are formed
by using the same manufacturing method. Hereinafter, a case where the
first member 14c and the second member 16c are formed by using silicon
will be described as an example.

[0067] FIGS. 7A to 7C are diagrams illustrating a method of manufacturing
the aperture plate according to the embodiment. First, as illustrated in
FIG. 7A, the first member 14c is formed by processing a silicon substrate
by etching. Next, as illustrated in FIG. 7B, the second member 16c is
formed by using the same manufacturing method as the first member 14c.
Next, as illustrated in FIG. 7C, the second member 16c is allowed to be
oriented in the reverse direction, and the second member 16c is allowed
to be adhered to the first member 14c. The adhesion may be performed by
using an adhesive. Otherwise, the surfaces of the two members may be
polished, and the two members may be adhered to each other by pressure.

[0068] According to the embodiment, since the first member 14c and the
second member 16c are manufactured in the same process, it is possible to
easily manufacture the aperture plate.

Fourth Embodiment

[0069] The embodiment is the same as the first embodiment except that, in
the end portion of the first opening portion, an air gap exists in an
interface between the first member and the second member. Therefore,
descriptions on overlapping portions with the first embodiment are not
presented.

[0070]FIG. 8 is a schematic cross-sectional diagram illustrating a
structure of an aperture plate according to the embodiment. As
illustrated in this figure, in the end portion of the first opening
portion 12, an air gap is installed in an interface between the first
member 14d and the second member 16d.

[0071] According to the embodiment, when electrons are blocked by the
second member 16d, the second member 16d is heated by the energy of the
electrons, and thus, the second member may be thermally deformed.
However, since an air gap exist between the second member 16d and the
first member 14d, the deformation is not easily transferred to the first
member 14d, particularly, the end portion of the opening portion.
Therefore, the deformation of the first member 14d cannot easily occur,
and deterioration in beam shaping accuracy is suppressed.

[0072] The size of the air gap is appropriately determined by considering
influence of the heat deformation of the second member 16d on the first
member 14d, easiness of the processing, and the like. For example, in
FIG. 8, the length of the air gap in the horizontal direction is in a
range of 1 μm to 5 μm, and the width of the in the vertical
direction is in a range of 0.5 μm to 2 μm.

Fifth Embodiment

[0073] The embodiment is the same as the first embodiment except that the
aperture plate further includes a second opening portion having an area
smaller than that of the first opening portion and a third opening
portion having the same shape as that of the second opening portion, and
positions of the end portions of the second and third opening portions in
the second member are recessed from the positions of the end portions of
the second and third opening portions in the first member. Therefore,
descriptions on overlapping portions with the first embodiment are not
presented.

[0074] FIGS. 9A and 9B are schematic diagrams illustrating a structure of
an aperture plate according to the embodiment. FIG. 9A is a top diagram,
and FIG. 9B is a cross-sectional diagram taken along line BB of FIG. 9A.

[0075] The aperture plate 50 includes a second opening portion 22 having
an area smaller than that of the first opening portion 12 and a third
opening portion 24 having the same shape as that of the second opening
portion 22. With respect to the second opening portion 22 and the third
opening portion 24, when the aperture plate is manufactured by adhering
the first member 14e and the second member 16e, the two opening portions
function as the alignment marks for the alignment. Therefore, the
alignment accuracy of the first member 14e and the second member 16e is
improved.

[0076] In addition, the second opening portion 22 or the third opening
portion 24 having a small area may be used as a monitor mark for
monitoring, for example, beam intensity distribution of the electron
beam. In terms of the use as a monitor mark, the second and third opening
portions 22 and 24 preferably have a square shape or a circular shape.
However, the second and third opening portions 22 and 24 may have an
oblong shape or other shapes.

[0077] In addition, in terms of the use as an alignment mark for the
alignment, the sizes of the second and third opening portions 22 and 24
are preferably small. In terms of this point, the sides or diameters of
the second and third opening portions 22 and 24 are preferably 1 μm or
less.

[0078] In addition, a fourth opening portion may be further formed, and
thus, three alignment marks are provided, so that the alignment accuracy
may be further improved.

[0079] According to the embodiment, it is possible to easily manufacture
the aperture plate, so that the manufacturing accuracy is improved.
Therefore, for example, it is possible to easily reduce the recessed
amount of the second member 16e from the end portion of the opening
portion of the first member 14e. In addition, it is also possible to
monitor an electron beam intensity distribution.

Sixth Embodiment

[0080] The embodiment is the same as the first embodiment except that the
shapes of the opening portions are different. Therefore, descriptions on
overlapping portions with the first embodiment are not presented.

[0081] FIG. 10 is a schematic top diagram illustrating a structure of an
aperture plate according to the embodiment. The opening portion 12 of the
aperture plate 60 does not have a rectangular shape but a combination of
a rectangular shape and a hexagonal shape.

[0082] According to the embodiment, for example, by further combining one
rectangular aperture plate on the upper portion thereof, the electron
beam can be shaped in a triangular shape or other polygonal shapes
besides the rectangular shape.

Seventh Embodiment

[0083] A charged particle beam writing apparatus according to the
embodiment includes a stage which a sample can be mounted thereon, an
irradiation unit which emits a charged particle beam to be irradiated on
the sample, and an aperture plate which includes a plurality of opening
portions to form multi-beams by allowing a region including all the
plurality of opening portions to be irradiated with the charged particle
beam and allowing portions of the charged particle beam to pass through
the plurality of opening portions. In addition, the aperture plate has a
stacked structure of the first member and the second member, and the
position of the end portion of the opening portion of the second member
is recessed from the position of the end portion of the opening portion
of the first member.

[0084] The charged particle beam writing apparatus according to the
embodiment is a multi-beam type writing apparatus which writes using a
plurality of electron beams. In the first to sixth embodiments, the
examples of the aperture plate used for variable shaping in which an
electron beam is shaped in an arbitrary shape are described. However, the
embodiment is different from the first to fifth embodiments in that an
aperture plate used for shaping multi-beams is exemplified. With respect
to the structure, material, function, and the like of the opening portion
of the aperture plate, description of some of the overlapping contents
with the first to fifth embodiments will not be presented.

[0085] FIG. 11 is a diagram illustrating a concept of a configuration of
the writing apparatus according to the embodiment.

[0086] In FIG. 11, the writing apparatus 500 includes a writing unit 150
and a control unit 160. The writing apparatus 500 is an example of a
multi-beam type charged particle beam writing apparatus. The writing
apparatus 500 writes a desired pattern on a sample 101.

[0087] The writing unit 150 includes an electron barrel 102 and a writing
chamber 103. An electron gun 201, an illumination lens 202, an aperture
plate 203, a blanking plate 304, a reduction lens 305, a limitation
aperture plate member 306, an objective lens 207, and a deflector 208 are
disposed within the electron barrel 102.

[0088] In addition, an XY stage 105 is movably disposed within the writing
chamber 103. In addition, the sample 101 is mounted on the XY stage 105.
As an example of the sample 101, there is a mask substrate for an
exposing process of transferring a pattern on a wafer. As an example of
the mask substrate, there is a blank mask where no image is written.

[0089] The control unit 160 includes a driving circuit 108, a magnetic
disc device 109, a deflection control circuit 110, digital-to-analog
converters (DACs) 112 and 116, a control calculator 120, and a memory
121.

[0090] The writing data stored in the magnetic disc device 109 are input
to the control calculator 120. Information input to the control
calculator 120 or information during an operation process and after the
operation process is stored in the memory 121 on each occasion.

[0091] The memory 121, the deflection control circuit 110, and the
magnetic disc device 109 are connected to the control calculator 120 via
a bus (not shown). The deflection control circuit 110 is connected to
DACs 112 and 116. The DAC 112 is connected to the blanking plate 304. The
DAC 116 is connected to the deflector 208.

[0092] FIG. 11 illustrates components necessary for description of the
embodiment. It is obvious that the writing apparatus 500 generally
includes other necessary components.

[0093] Hereinafter, the writing method of the writing apparatus 500 will
be described with reference to FIG. 11.

[0094] An electron beam 200 is emitted from the electron gun 201 as an
example of the irradiation unit. The electron beam 200 emitted from the
electron gun 201 is illuminated on the entire aperture plate 203 in
almost the vertical direction through the illumination lens 202.

[0095] A plurality of rectangular, for example, oblong or square holes
(opening portions) are formed in the aperture plate 203, and the electron
beam 200 is illuminated on a region including all the plurality of holes.
The electron beam is allowed to pass through the plurality of the holes
of the aperture plate 203, so that, for example, a plurality of
rectangular electron beams (multi-beams) 200a to 200e are formed.

[0096] The multi-beams 200a to 200e pass through blankers corresponding to
the blanking plates 304. The blankers deflect the electron beams 200a to
200e which individually pass through the blankers.

[0097] The multi-beams 200a to 200e passing through the blanking plates
304 are reduced by the reduction lens 305 and propagate toward a central
hole formed in the limitation aperture plate member (blanking aperture
plate) 306. Herein, the multi-beams 200a to 200e deflected by the
blankers of the blanking plates 304 are deviated from the central hole of
the limitation aperture plate member 306, so that the multi-beams are
blocked by the limitation aperture plate member.

[0098] On the other hand, the multi-beams 200a to 200e which are not
deflected by the blankers of the blanking plates 304 pass through the
central hole of the limitation aperture plate member 306. Blanking
control is performed by the on/off of the blankers, so that the on/off of
the beams can be controlled.

[0099] In this manner, the limitation aperture plate member 306 blocks the
beams which are deflected so that the beams are allowed to be in the off
states by the plurality of the blankers. Next, a beam of one shot is
formed from the beams which are formed in a time interval from the time
when the beam allowed to be in the on state to the time when the beam
allowed to be in the off state and which pass through the limitation
aperture plate member 306.

[0100] The multi-beams 200a to 200e passing through the limitation
aperture plate member 306 are focused on one point by the objective lens
207 to form a pattern image with a desired reduction ratio. The beams
(all the multi-beams 200a to 200e) passing through the limitation
aperture plate member 306 are collectively deflected in the same
direction by the deflector 208, so that the beams are irradiated on the
positions of the sample 101.

[0101] In addition, the irradiation position of the beam is controlled by
the deflector 208 so that the irradiation position of the beam follows
the movement of the XY stage 105, for example, when the XY stage 105 is
continuously moved. Ideally, the multi-beams 200a to 200e which are
irradiated at one time are arranged at a pitch which is a product of an
arrangement pitch of a plurality of the holes of the aperture plate and
the above-described desired reduction ratio.

[0102] When the writing apparatus 500 performs a writing operation in a
raster scan method of continuously irradiating shot beams in sequence to
write a desired pattern, unnecessary beams are controlled through
blanking control so as to be in the beam off state.

[0103] FIGS. 12A and 12B are schematic diagrams illustrating a structure
of an aperture plate according to the embodiment. FIG. 12A is a top
diagram, and FIG. 12B is a cross-sectional diagram illustrating one
opening portion.

[0104] In the embodiment, an aperture plate 70 of FIGS. 12A and 12B is
applied to the aperture plate 203 of FIG. 11.

[0105] Holes (opening portions) 12 of vertical (y direction) m
rows×horizontal (x direction) n columns (m, n≧2) are formed
with a predetermined arrangement pitch in the aperture plate 70. In FIG.
12A, for example, 8×8 opening portions 12 are formed. The opening
portions 12 are formed to have the same rectangular shapes, for example,
oblong shapes or square shapes having the same dimensions. Alternatively,
the opening portions 12 may be formed to have circular shapes having the
same outer diameter.

[0106] Portions of the electron beam 200 are allowed to pass through the
plurality of the opening portions 12, so that the multi-beams 200a to
200e are formed.

[0107] In addition, with respect to the arrangement of the opening
portions, although the example where the same number of opening portions
are arranged in the horizontal and vertical directions are described as
illustrated in FIG. 12A, the embodiment is not limited to the
arrangement. For example, different numbers of the opening portions may
be arranged in the horizontal and vertical directions. In addition, for
example, the opening portions of the adjacent horizontal columns or
vertical rows may be arranged to be deviated by a predetermined
dimension.

[0108] As illustrated in FIG. 12B, similarly to the first embodiment, the
aperture plate 70 has a stacked structure of the first member 14a and the
second member 16a. In the embodiment, the second member 16a is disposed
on the side of the electron gun 201. In other words, the upper surface of
the second member 16a is configured to be irradiated with the electron
beam.

[0109] The first member 14a and the second member 16a are formed by using
the same material, for example, silicon. As a material which can be used
for existing semiconductor processes during the manufacturing and of
which impurities can be reduced, the silicon can be preferably used.
Furthermore, a semiconductor such as silicon nitride, silicon carbide, or
silicon germanide, a metal, or a metal compound may be used.

[0110] In addition, as illustrated in FIG. 12B, the position of the end
portion (edge of opening portion) of the first opening portion of the
second member 16a is recessed from the position of the end portion (edge
of opening portion) of the first opening portion of the first member 14a.
In other words, the opening portion of the second member 16a is larger
than the opening portion of the first member 14a, and the first member
14a and the second member 16a are stacked so that the end portions of the
opening portions thereof do not overlap each other.

[0111] According to the charged particle beam writing apparatus of the
embodiment, it is possible to implement the charged particle beam writing
apparatus capable of securing shaping accuracy of the multi-beams and
suppressing drift of the charged particle beam. In addition, according to
the writing method using the charged particle beam writing apparatus of
the embodiment, it is possible to perform writing at high accuracy by
securing the shaping accuracy of the multi-beams and suppressing drift of
the charged particle beam.

[0112] In addition, herein, although the case in which the same structure
as that of the first embodiment is applied to the opening portion of the
aperture plate of the multi-beam type writing apparatus are described as
an example, the same structures as those of the second or fifth
embodiments may be applied.

[0113] Hereinbefore, the embodiments are described with reference to
specific examples. However, the present disclosure is not limited to the
specific examples.

[0114] In addition, although description of components such as
configurations of an apparatus or control methods which are not directly
needed for the description of the present disclosure is not presented,
necessary configurations of the apparatus and necessary control methods
may be appropriately selected to be used. For example, although
description of configurations of the control unit of the writing
apparatus 100 is not presented, it is obvious that necessary
configurations of the control unit may be appropriately selected to be
used.

[0115] In addition, all charged particle beam writing apparatuses and
charged particle beam writing methods, which are configured to include
the components of the present disclosure and can be modified in design by
the skilled person in the art, belong to the scope of the present
disclosure.